Attenuator for a wide range of frequencies

ABSTRACT

An attenuator for a wide range of frequencies has a dielectric plate supported within first and second outer-conductors. A rectangular resistive member is deposited on the surface of the dielectric plate and is contiguously interposed between two pairs of highly conductive electrodes. An impedance compensation member having substantially the same shape as the rectangular resistive member is deposited on either the inner surface of the first outer-conductor or the second outer-conductor so as to at least compensate for variation of the characteristic impedance produced when a high frequency current flows in the electrodes.

' United States Patent Tomimura ATTENUATOR FOR A WIDE RANGE OF FREQUENCIES Noboru Tomimura, Tokyo, Japan Iwatsu Electric Co., Ltd., Tokyo, Japan Oct. 17, 1974 Inventor:

Assignee:

Filed:

App]. No.:

Foreign Application Priority Data Oct. 20, 1973 Japan 48-118118 US. Cl. 333/81 A; 333/33 Int. Cl. HOlP 1/22 Field of Search 333/33, 81 R, 81 A References Cited UNITED STATES PATENTS 7/1970 Veteran .l....-333/s1 A IMPEDANCE COMPENSATION MEMBER 1 Oct. 28, 1975 3,761,846 9/1973 Tsuboi 333/33 Primary Examiner=Paul L. Gensler Attorney, Agent, or F irm-Oblon, Fisher & Spivak, McClelland & Maier [5 7] ABSTRACT An attenuator for a wide range of frequencies has a dielectric plate supported within first and second outer-conductors. A rectangular resistive member is deposited on the surface of the dielectric plate and is contiguously interposed between two pairs of highly conductive electrodes. An impedance compensation member having substantially the same shape as the rectangular resistive member is deposited on either the inner surface of the first outer-conductor or the second outer-conductor so as to at least compensate for variation of the characteristic impedance produced when a high frequency current flows in the electrodes.

5 Claims, 17'Drawing Figures COMPENSATION MEMBER RESISTIVE MEMBER U.S. Patent Oct.28, 1975 Sheetl0f6 3,916,354

FIG.

PRIOR ART US. Patent Oct. 28, 1975 A Sheet 2 of6 3,916,354

FIG.3

IMPEDANCE COMPENSATION MEMBER IMPEDANCE COMPENSATION MEMBER YRESISTIVE MEMBER US. Patent Oct. 28, 1975 Sheet3of6 3,916,354

US. Patent Oct. 28, 1975 Sheet4of6 3,916,354

Sheet 5 of 6 3,916,354

U.S. Patent 0a. 28, 1975 FIG.

US. Patent Oct. 28, 1975' Sheet6of6 3,916,354

FIG. I?

A 4 \& A -imi 425A ii ATTENUATOR FOR A WIDE RANGE OF x FREQUENCIES BACKGROUNDOF THE INVENTION,

l.Field'ofthe Invention a This invention relates in general to an attenuator for a wide range of frequencies and more particularly to attenuators with extremely little variation in characteristic impedance and in attentuation over the wide frequency range. V

2. Description of the Prior Art US. Pat. No. 3,227,975 is exemplary of prior art attenuators and discloses a distributed network resistive film attenuator.

This invention provides for an attenuator which is based on the attenuator of the above-mentioned patent and which improves the defects which result from the conventional,attenuator. f 1

It is generally known from electromagnetic theory that the lines of magnetic force or of electric force distort due to the discontinuity of an inductivity and permeabilit'y. Thus, for example, in the conventional distributed network resistive film attenuator a resistive film is provided contiguously interposed between a pair of highly conductive electrodes so that when current high frequency flows in the highly conductive electrodes thelines of electric force distort.

Accordingly, the conventional attenuator as shown in FIG. 1 having the same principle of operation as the attenuator disclosed in the above-mentioned patent has certain defects in that when a current I, at a microwave frequency flows in highly conductive electrodes 5a, 5b, the characteristic impedance Zo varies and a variation in attenuation occurs wherein a load having an impedance 20 equal to the characteristic impedence Z is connected between the electrode b and an outer: conductor 2 as shown in FIG. 2. For this reason, where the current I flows in highly conductive electrodes 5a, 5b, lines of electric force are generated perpendicular to the electrodes 5a, 5b, and reach the inner surface of outer-conductors 1', 2. On the other hand where the current I flows in a resistive member contiguously interposedbetween a pair of electrodes 5a, 5b, thenthe lines of electric force reach the inner surfaces of the outer-conductors l, 2 causing the distortion line as shown in FIG. 2, wherein 41 4);, and d), designate emission angles respectively and 4 designates a dielectric plate. The length of the lines of electric force from a resistive member 6a to the inner surfaces of the outer conductors l, 2 is longer than the lines of electric force from the electrodes 5a, 5b to the inner surfaces of the outer-conductors l, 2. As a result thereof when a current having a high frequency flows in the electrodesSa, 5b then the frequency sensitivity of VSWR representing variation in the characteristic impedance Z0 is large so as to result in reflection of current at high frequencies and variation in attenuation.

SUMMARY OF THE INVENTION. v I Accordingly, it is an object of this inventionto. provide a new and improved unique widebandattenuator,

,for example in the range of DC. to l8GI-Iz;

It is still another object of this invention to provide a new and improved uniqueattenuatorwhich minimizes variation in characteristic impedance so as to provide a substantially constant attenuation with high frequency. I

Briefly, in accordance with this invention, theforego- 'ing and other objects are provided by anattenuator plate and contiguously interposed between two pairs of highly conductive electrodes. ,An impedance compensation member having substantially the same shape as the rectangular resistive member is.dep osited on at least either the inner surface of the first conductoror the second outer-conductor so as to compensate for variation in characteristic impedance. Zo produced when a high frequency current flows in the highlyconductive electrodes.

, BRIEF DESCRIPTION THE DRAWING Other objects and features of the invention will become apparent to thoseskilled in the art as the disclosure is made in the following description of preferred embodiments of the invention, as illustrated in the accompanying sheets of drawings, in which like reference characters designate the same orsimilar, parts throughout the several figures thereof and wherein;

FIG. 1 shows a cutaway view, partly in section, of a conventional attenuator, I FIG. 2 illustrates a side andcutaway'view of the attenuator shown in FIG. 1. a

FIG. 3 shows a perspective view and a cutawayview, partly in section, of a first preferred embodiment of the invention. r p

FIG. 4 and FIG. 5 are front and sideviews of the attenuator shown inFIG. 3 respectively.

FIG. 6 shows a perspective and a cutaway view, partly in section, of a second preferred embodiment of the invention. V

FIG. 7 and FIG. 8 are frontand side views of the-attenuator shown in FIG. 6 respectively. FIG. 9 illustrates a perspective view and acutaway view, partly in section, of a third preferred embodiment of the. invention.

FIG. ,10.and FIG. 11 are front and side views of the attenuator shown in FIG. 9 respectively.

FIG. 12 shows a perspective view and a cutaway view, partly in section, of a fourth preferred embodiment of the invention.

FIG. 13' and FIG. 14 are front and side views of the attenuator shown in FIG. 12 respectively.

FIG. 15 and FIG. 16v show perspective views and cutaway views, partly'in section, of fifth andsixth preferred embodiments of the invention respectively.

- FIG. 17 shows a front view of a seventh preferred embodiment of the invention DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first preferred embodiment of the invention will be explained by referring to the drawings of FIG. 3, FIG. 4 and FIG. 5. The first embodiment shows a bidirectional attenuator. i

The numerals 1 and 2 designate afirstand .a second outer conductor respectively, both .of which are provided with U shaped grooves. A set of the first and secand outer conductors 1, 2 forms a,hollow conductor'3.

' The lengthwise upper edges of the inner wall sides of the, first and second outer conductors l, 2 are provided with an L shaped notch, a set. of which forms shaped grooves. Adielectric plate 4-,is in the shaped grooves so as to-be supported by the-grooves. A rectangular resistive member 6a is deposited on thesurface ofthe dielectric plate 4 by sputtering techniques and the like which are well known in the art and contiguously interposed between third conductors 5a, 5b and fourth con-'v ductors 7, 8. The third conductors 5a, 5b are highly conductive electrodes and are provided on a central portion of the dielectric plate 4 through the rectangular resistive member 6a. The fourth conductors 7, 8 are disposed between the outer conductors l, 2 and the lengthwise edges of the rectangular resistive member 60 along the full length thereof so as to provide electrical signal connections. The entire area of the rectangular resistive member 6a is made to have equal values of resistance.

First and second impedance compensation members 9a, 10a having substantially the same shape as the first rectangular member 6a are deposited on the inner surfaces of the first and second conductors l, 2 respectively and are positioned above and under the rectangular resistive member 6a so as to compensate for variation in characteristice impedance Z produced when a high frequency current flows in the electrode a, 5b.

I The impedance compensation members 9a, a may be a high frequency current I, or flows in the electrode 5b. As shown in FIG. 5, the width of the impedance compensation members 9a, 10a are designed to be longer than the width W of the rectangular resistive member 6a. The above-mentioned positions A and A are generally obtained by a conventional means of drawing figures based on emission angles 42 and (I), and the like or calculation of the lines of electric force.

As shown in FIG. 4, when a current I or I' having a high frequency flows in the third conductors 5a, 5b, then the lines of electric force will radiate from the third conductors 5a, 5b or the rectangular resistive member 6a as shown in the drawing by a dotted line curve. The thickness of the impedance compensation members 9a, 100 are designed so that the distance of the radiated electric force lines from the third conductors 5a, 5b to the inner surfaces of the first and second conductors l, 2 is equal to the distance of the radiated electric force lines from the rectangular resistive member 6a to the impedance compensation members 9a, 10a. A As a result thereof variation in characteristic impe dance 20 is drastically minimized and the line having the characteristic impedance Z0 includes the third conductors 5a, 5b of width W the fourth conductors 7, 8 and the hollow conductor 3. I

FIG. 6, FIG.'7 and FIG. 8 show a second preferred embodiment of the present invention. The embodiment of FIG. 6, FIG. 7 and FIG. 8 shows a bi-directional attenuator wherein the impedance compensation member 91) is deposited only on the first outer-conductor 1. In this case, the impedance compensation member 9b is designed to be thicker than the impedance compensation members 9a, 10a of the attenuator as shown in FIG. 3'since the impedance match is not as good as that of the embodiment of FIG. 3.

FIG. 9, FIG. 10 and FIG. 11 show a third preferred embodiment of the present invention. The embodiment of-FIG. 9, FIG. lOand FIG. 11 shows a bi-directional attenuator wherein the impedance compensation member 10b is deposited only on the second outerconductor 2. The impedance compensation member 10b is designed to be thicker than the impedance compensation members 9a, 10a of FIG. 3 like in the embodiment of FIG. 6, FIG. 7 and FIG. 8.

FIG. 12, FIG. 13 and FIG. 14 show a fourth preferred embodiment of this invention. This embodiment is a bidirectional attenuator. As shown in FIG. 12, FIG. 13 and FIG. l4 a rectangular resistive member 6b and third conductors 5a, 5b form a T shape-pattern. In this case, impedance compensation members 9c, 10c are deposited on the inner surfaces of the outer-conductor l, 2 so as to be positioned above and under the rectangular resistive members 1, 2 respectivelyand so as to compensate for variation in the characteristic. impedance produced when a high frequency current flows in the electrodes 5a, 5b.

FIG. 15 and FIG. 16 show bi-directional attenuators of a fifth and a sixth preferred embodiments of the present invention wherein impedance compensation members 9d or 10d are deposited either on the first outerconductor l or on the second outer-conductor 2.

The embodiments of FIG. 15 and FIG. 16 have the same effect as the embodiment of FIG. 3, FIG. 4 and FIG. 5.

It should be understood that this invention is applicable to a single directional attenuator as well as a bidirectional attenuator. In this case, as shown by example in FIG. 17, the side edge of the impedance compen sation members 9e and We having the same shape as the rectangular resistive member 6e are deposited on position A, A of the inner surfaces of the first and second outer-conductors l, 2 such that the lines of electric force radiated from boundary B or B of the electrode 5d or 5b and the rectangular resistive member 6e will reach the same when a high frequency current I flows in the electrode 5a.

As mentioned above, in accordance with this invention, it is apparent that variation in characteristic impedance and attenuation can be minimized over a wid frequency band.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be covered by letters patent is:

1. An attenuator having upper and lower contiguous outer-conductors and a pair of coaxial inner conductors comprising:

a. a dielectric plate supported within said upper and I lower outer conductors,

b. a first pair of electrodes connected to said upper and lower outer conductors,

c. a second pair of electrodes connected to said coaxial inner conductors,

d. a rectangular resistive member deposited on said dielectric plate and contiguously interposed between said first pair of electrodes and said second pair of electrodes, and

e. an immpedance compensation member having substantially the same shape as said rectangular resistive member and deposited on at least either the inner surface of said upper outer-conductor or the inner surface of said lower conductor for compensating for variation in characteristic impedance.

2. An attenuator according to claim 1, wherein said impedance compensation member comprises a conductive member.

3. An attenuator to claim 1 wherein, both edges of -the impedance compensation member are deposited at c. a second pair of electrodes connected to said coaxial inner conductors,

d. a rectangular resistive member deposited on said dielectric plate and contiguously interposed between said first electrode and said second pair of electrodes, wherein said resistive member and said second pair of electrodes form a T-shaped pattern, and

e. an impedance compensation member having substantially the same shape as said rectangular resistive member and deposited on at least either the inner surface of said upper outer-conductor orthe inner surface of said lower outer-conductor for compensating for variation in characteristic impedance.

5. An attenuator according to claim 4 wherein, both edges of the impedance compensation member are deposited at a position at least on either inner surface of the outer conductors such that lines of electric force radiated from the boundaries of the rectangular resistive member and the electrodes will respectively reach said compensation member. 

1. An attenuator having upper and lower contiguous outerconductors and a pair of coaxial inner conductors comprising: a. a dielectric plate supported within said upper and lower outer conductors, b. a first pair of electrodes connected to said upper and lower outer conductors, c. a second pair of electrodes connected to said coaxial inner conductors, d. a rectangular resistive member deposited on said dielectric plate and contiguously interposed between said first pair of electrodes and said second pair of electrodes, and e. an impedance compensation member having substantially the same shape as said rectangular resistive member and deposited on at least either the inner surface of said upper outerconductor or the inner surface of said lower conductor for compensating for variation in characteristic impedance.
 2. An attenuator according to claim 1, wherein said impedance compensation member comprises a conductive member.
 3. An attenuator to claim 1 wherein, both edges of the impedance compensation member are deposited at a position at least on either inner surface of the outer conductors such that lines of electric force radiated from the boundaries of the rectangular resistive member and the electrodes will respectively reach said compensation member.
 4. An attenuator having upper and lower contiguous outer-conductors and a pair of coaxial inner conductors comprising: a. a dielectric plate supported within said upper and lower outer conductors, b. a first electrode connected to one of upper and lower said outer-conductors, c. a second pair of electrodes connected to said coaxial inner conductors, d. a rectangular resistive member deposited on said dielectric plAte and contiguously interposed between said first electrode and said second pair of electrodes, wherein said resistive member and said second pair of electrodes form a T-shaped pattern, and e. an impedance compensation member having substantially the same shape as said rectangular resistive member and deposited on at least either the inner surface of said upper outer-conductor or the inner surface of said lower outer-conductor for compensating for variation in characteristic impedance.
 5. An attenuator according to claim 4 wherein, both edges of the impedance compensation member are deposited at a position at least on either inner surface of the outer conductors such that lines of electric force radiated from the boundaries of the rectangular resistive member and the electrodes will respectively reach said compensation member. 